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Seismic vulnerability of speleothems may serve long-term seismic risk studies. For this reason, the seismic response of stalagmite is computed using a robust FEM model calibrated from free vibration records by Hilbert–Huang modal extraction. It is demonstrated that the stalagmite vibrations consist of pairs of closely coupled flexural natural modes with a negligible role of vertical excitations. The location of the breaking point of the stalagmite is a result of a balance between the overturning bending moment and variations of horizontal cross-sections with height. Safety margins are investigated, and the ultimate peak velocity of excitations equaling 3.4 mm/s is estimated. [ABSTRACT FROM AUTHOR]

Due to rapid urbanization, open excavations are not uncommon these days. However, many issues are arising during the execution of unsupported open excavations when not designed and executed properly. Moreover, in urban areas where new buildings are constructed closer to the existing buildings, these excavations may affect the structural integrity of the adjacent existing buildings. Therefore, there is a need to evaluate the response of multistorey building frame (MBF) subjected to nearby series of unsupported open excavations. In the study, a numerical investigation on response of RCC-MBF structure with raft foundation resting on medium dense sand subjected to adjacent unsupported open excavations is performed using a 3D finite element program PLAXIS-3D. The series of open excavation is simulated considering the different geometrical parameters of excavation, such as varying setback distance, and different excavation volumes. As a response, the four parameters are monitored in the columns of the MBF i.e., displacement of the structure in x- and z-directions (i.e., settlement and tilt), and redistributed bending moments and shear forces in the column of MBF. The linear and non-linear analyses are performed to account the effect of constitutive models on the response of the MBF by assigning the Linear–Elastic and Mohr–Coulomb soil constitutive models to the soil respectively. Further, a sensitivity analysis is performed to evaluate the effect of strength and deformation parameters of the soil, and the geometrical parameters of the excavation on the factor of safety of excavation slope. Based on the results, it is observed that Mohr–Coulomb constitutive model can be used to analyse the response of structure subjected to unsupported open excavations. Finally, the effect of different foundation schemes is also analysed in the study. [ABSTRACT FROM AUTHOR]

Segmental lining is subject to significant upward buoyancy forces when a grouting material (slurry), initially fluid, is adopted to fill the gap between its external profile and the wall of a tunnel excavated with a TBM machine. The analysis of the effects of these forces is important in order to correctly dimension the segmental lining and avoid damage to the lining and subsequent costly maintenance and restoration actions. Given the complexity of the behavior of a segmental lining consisting of segmental rings and circular joints that alternate in the longitudinal direction of the tunnel, a specific numerical model has been implemented, adopting the Finite Element Method (FEM). This model is able to obtain the development of the vertical displacements of the segmental lining starting from the TBM tail, together with the bending moments and the shear forces induced inside it. The developed model is able to assess the risks of breaking and damaging the concrete and steel bolts that are used to connect the segmental rings at the circular joints; therefore, it represents a useful design tool for being able to correctly dimension the segmental lining also in relation to the risks produced by the appearance of considerable buoyancy forces around it, due to the presence of the initially fluid filling material. The proposed numerical model was applied to a real case (Ningbo metro tunnel) and allowed to obtain satisfactory results from the comparison of the calculated displacements with in situ measurements. Some sensitivity analyzes developed on the studied case have made it possible to detect which are the influencing parameters that have the greatest impact on the behavior of segmental lining in the presence of the studied buoyancy forces. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In all types of new arch bridge structures, the requirements of the foundation are becoming more and more strict. Under the action of horizontal thrust, the distribution of the internal forces of the pile group in which inclined piles participate in an arch foundation is complicated. In this regard, the horizontal forces of each pile in a pile group and the horizontal bearing performance of each pile in a pile group under the action of total thrust are investigated by establishing a pile group foundation model and a p-y curve difference equation. After an in-depth analysis of the simulation results, it is found that the load distribution calculated by the finite element method is very close to that calculated by the p-y curve method, both in terms of curve shape and numerical value, indicating that the pile top load distribution is close to the actual situation. In addition, the maximum shear force of each pile body occurs at the top of the pile, and the maximum bending moment occurs at the point 1/5 away from the top of the pile. Finally, the nonlinear analysis of the p-y curve method can be well applied to the calculation of bridge pile foundations. [ABSTRACT FROM AUTHOR]

Tire-derived aggregate (TDA) has been used successfully as a backfill soil to reduce the applied stresses on buried steel pipes. The preceding study, however, paid no attention to inspecting the TDA efficiency of buried concrete pipes subjected to soil and traffic loads. In addition, it is not clear how the TDA material, traffic loading, burial depth, and road section affect the pipe-bending moment. Therefore, this paper examines the efficiency of TDA in reducing the bending moment of a 0.6 m concrete pipe subjected to combined soil and traffic loads using a validated three-dimensional finite element model. Two trench configurations have been constructed, the first is composed completely of well graded sand, and the second is similar to the first except for the 150 mm layer on the top of the pipe crown, which is replaced with TDA. Furthermore, three road sections (highway, public road, and unpaved road) have been adopted to provide an intensive understanding of the TDA effect for different road conditions. A parametric study is carried out to detect the effect of the burial depth, road section, and traffic load on the efficiency of the TDA of the buried pipe. It is observed that the TDA has no effect on the bending moment distribution around the pipe. Additionally, the TDA reduces the bending moment developed in the pipe wall with a percentage decrease range between 18% and 42% depending on the burial depth and road section. Furthermore, it is also found that the efficiency of the TDA in reducing the maximum bending moment decreases as the burial depth increases. In addition, the best performance for the TDA is found at a burial depth of 1.0 m for all road sections. Importantly, the best performance for the TDA is found for the highway section compared with the other sections, with a maximum percentage decrease of 42% compared to 27% for the public road section and 26% for the unpaved road section. [ABSTRACT FROM AUTHOR]

The interspersed railway track is an enhanced timber railway track, spot-replacing damaged wooden sleepers with new concrete sleepers to improve the bearing capacity of existing railway lines. Although this interspersed solution is characterised by low cost and short maintenance time, the interspersed tracks have worse stability than concrete tracks and can deteriorate quickly when exposed to extreme weather conditions such as heavy rains and floods. In many cases, heavy rains and floods are accompanied by strong winds. Ballast washaway can often be observed under flood conditions while the mass of trains is unevenly distributed on two rails due to the effect of lateral wind load and rail irregularities. The current work is the first in the world to investigate the collective multi-hazard effects of ballast washway and uneven axle loads on the vulnerability of conventional and interspersed railway tracks using nonlinear FEM software, STRAND 7. The train bogie is modelled by two sets of point loads. The maximum displacement, bending moment and twists have been studied to evaluate the worst condition. The novel insights will help the railway industry develop proper operations of interspersed railway tracks against naturally hazardous conditions. [ABSTRACT FROM AUTHOR]

The study presents the design forces of simply supported single-cell reinforced concrete (RC) curved box-girder bridges using a finite element method (FEM) based CSiBridge v.20 software. An existing model has been used to validate the present modelling approach. Models subjected to vertical loading, i.e., dead load (DL) and Indian road congress live load (LL), are considered for investigation. An intensive parametric study examines the maximum values of bending moment (BM), shear force (SF), torsional moment (TM), and vertical deflection (VD) in both girders of bridges. The influences of curve angle and span are considered in the study. The effect of curve angle, up to 12°, is negligible on forces and deflections, and thus such bridges can be analysed as a straight one. Finally, non-dimensional equations are derived for evaluating forces and deflections, so that one may predict these quantities for curved bridges based on straight bridge's results. Engineers and designers may consider present work valuable in analysing, and designing curved box-girder bridges. [ABSTRACT FROM AUTHOR]

This paper focuses on investigating the structural behavior of members and connections that are part of moment frames under the combined effect of bending moment and thermally induced axial force during a compartment-fire event. The finite-element analysis method was employed to conduct this study using models benchmarked against experimental data from several past studies while utilizing temperature-dependent material models. A numerical parametric study on typical floor beams with slender elements for compression were conducted under combined bending and axial loading to develop interaction-capacity curves at temperatures representing fire events. The results were compared against the member-strength equations provided in the AISC Specification. The analysis results demonstrated that the AISC beam-column strength equations including the combined effects of axial-load and bending moment provided reasonable estimates for member-slenderness ratios greater than 60, but overestimated the strength of beams with slender elements for low member-slenderness ratios. Combined-load-strength studies were also conducted on a typical connection used in moment frames. The moment-connection behavior was governed by failure modes exhibited at the ends of floor beams. Therefore, the interaction equations available for beam columns resulted in conservative estimates and are recommended for calculating moment-connection capacity during compartment-fire scenarios. [ABSTRACT FROM AUTHOR]

This paper investigates a novel variable‐grade prefabricated concrete (PC) slab with surrounding composited which has high prefabrication rate, sufficient installation rigidity, high on‐site construction efficiency, and good overall working performance. To improve the crack‐resistance performance of the transverse superposed surface and the overall working performance of the proposed novel PC slab, we optimize the position of variable‐grade and arrange it at the location where the bending moment is close to zero. We perform comparatively bending tests on three two‐span full‐scale slab strips that include boundary and intermediate beam‐slab joints to systematically investigate the flexural behavior of the proposed novel slab. The load versus deflection relationship, failure mode, distribution of cracks, development law of crack width and development of steel strain are comparatively studied. The test results confirm that the flexural behavior of the proposed novel PC slabs are similar and slightly better than that of the cast‐in‐place slab in general. No crack or slippage appears at the interface between the precast panel and the post‐pouring concrete. The connection method of L‐shaped anchorage rebars lap splicing in this study is cost‐effective, efficient, and reliable. Furthermore, we establish a finite element model and perform a parametric investigation on the proposed novel PC slab. Parametric simulations conclude that the increase of the strength of post‐pouring concrete and post‐pouring layer thickness can improve the bearing capacity of the proposed novel PC slabs. [ABSTRACT FROM AUTHOR]

This paper presents experimental and numerical investigations on progressive collapse behavior of a two-story glulam frame when the side column is exposed to ISO834 standard fire. The collapse mechanism initiated by fire is identified. The experimental results show that the progressive collapse of a glulam frame could be described for three stages, namely bending effect stage, catenary effect stage and failure stage, respectively. These stages are discussed in detail to understand the structural behavior before and during collapse. It is demonstrated that the entire frame slopes towards the side of the heated column, and the "overturning" collapse occurs eventually. The catenary effect of beams is the main reason for the progressive collapse of the frame. In addition, a finite element model of a glulam frame is established to simulate the progressive collapse behavior. The effects of axial loads on the columns are summarized. The numerical simulation results agree well with the experimental results, which could verify the effectiveness and practicability of finite element simulation. Furthermore, the progressive collapse resistance of the frame in practical design were proposed. [ABSTRACT FROM AUTHOR]

Lead rubber isolation bearings are well-recognized as a common and effective means to mitigate the seismic responses of bridges. However, rubber isolation bearings used in offshore bridges are extremely vulnerable to the action of the alternation of aging and seawater erosion caused by weather conditions, wind, waves, and other factors. Meanwhile, the deterioration law and application of lead rubber bearings subject to the effect of aging and seawater erosion cycles are not clear. Thus, aging and seawater erosion cycles testing on both lead rubber isolation bearings (LRB) and rubber materials were carried out. The parameters for the Mooney–Rivlin model of the rubber material used in LRBs were determined and the time-varying law of basic performance of LRBs was obtained based on test results of LRBs and their rubber material. Then, the determined rubber material parameters were applied into the finite-element model of LRBs to verify the basic performance degradation law of the LRBs. Finally, the obtained basic performance degradation law of LRBs was substituted into the finite model of offshore bridges to investigate the impact of the property degradation of LRBs on their seismic performance. The time-varying law of seismic performance of offshore bridge structures was also studied based on finite element analysis. The results show that both the horizontal and vertical stiffness of LRBs increase with the alternating of aging and seawater erosion time, and the horizontal and vertical stiffness increase by 16.1% and 24.3%, respectively, during the 120-year service period. Additionally, the Mooney–Rivlin model parameters of the LRB rubber material are also significantly affected by the alternating of aging and seawater erosion. Additionally, the results also indicate the deterioration of LRBs has a great influence on the anti-seismic performance of offshore bridge structures. After 120 years of service of offshore bridge isolation bearings under the alternating of aging and seawater erosion, the maximum displacement of the pier top of the offshore bridges, the maximum bending moment at the pier bottom, and the maximum displacement of the rubber bearing increased by 14.2%, 6.6%, and 9.1%, respectively. The findings of this paper play an important role in the seismic behavior study and the life-cycle performance analysis of offshore traffic projects such as sea-crossing bridges in marine environments. At the same time, they also lay a theoretical foundation for the performance analysis of rubber isolation bearings and offshore bridge structures under the alternation of aging and seawater erosion cycles. [ABSTRACT FROM AUTHOR]

An inclined straight combination support pile can play a better role in deep foundation pit support, especially for the protection of adjacent structural pile foundations. We take a section of the construction of a deep foundation pit project in Wuhan City, Hubei Province as the research object. This paper studies the influence of inclined and straight combination support piles on the bending moment and displacement behavior of adjacent pile foundations during the construction of foundation pits under the influence of different factors such as distance from the excavation surface, pit angle effect, inclined pile tilt angle, pit depth to width ratio, and construction conditions on the adjacent pile foundation using a three-dimensional finite element model. According to the research results, as the distance from the excavation surface increases, the bending moment of the adjacent pile foundation decreases, and the closer the pile is to the foundation pit, the greater the horizontal displacement of the pile; the bending moment and displacement of the pile foundation are supported by the pit angle effect. Moreover, the pile bending moment increases with the increase of the pit depth–width ratio, and the maximum displacement point of the pile body gradually moves down from the middle of the pile body to the bottom of the pile foundation as the excavation depth of the pit increases. In addition, the minimum displacement of the adjacent pile foundation is at the top of the pile, and the maximum displacement is at the middle of the pile. Finally, compared with the static analysis, the whole process of dynamic simulation can reflect the dangerous working conditions in the project construction process, and make a more complete safety control construction plan for the project construction process. [ABSTRACT FROM AUTHOR]

BACKGROUND: In the treatment of osteoporotic vertebral compression fracture, bone-filling mesh container has a significant curative effect. Considering the operation time, lateral leakage of bone cement and the number of radiation exposure, unilateral approach is better. However, no study compared unilateral bone-filling mesh container and bilateral bone-filling mesh container from the perspective of biomechanics, lacking certain theoretical data support. OBJECTIVE: To investigate the biomechanical characteristics and clinical effects of unilateral and bilateral bone-filling mesh container approaches in the treatment of osteoporotic vertebral compression fracture. METHODS: (1) A finite element model was established to simulate the treatment of osteoporotic vertebral compression fracture with unilateral and bilateral bone-filling mesh container. The displacement and stress changes of the whole finite element model of thoracolumbar segment in the unilateral bonefilling mesh container group and bilateral bone-filling mesh container group were compared and analyzed under 400 N vertical downward loading force and 7.5 N·m bending moment load under four working conditions. (2) A retrospective analysis was performed on 99 patients with osteoporotic vertebral compression fracture who were treated with bone-filling mesh container from January 2018 to August 2020 in Wuhan Puren Hospital. Of them, 49 patients were treated with unilateral bone-filling mesh container and 50 patients were treated with bilateral bone-filling mesh container. Bone cement leakage rate, visual analogue scale score, and Cobb angle change were analyzed between the two groups. RESULTS AND CONCLUSION: (1) Finite element model: There was no significant difference in the maximum displacement between unilateral group and bilateral group under axial, forward flexion, left bending, and left rotation conditions (P > 0.05). There was no significant difference in the maximum stress between unilateral group and bilateral group under axial, forward flexion, left bending, and left rotation conditions (P > 0.05). (2) Clinical trial: The bone cement leakage rates in the unilateral and bilateral approach groups were 12% and 16%, respectively, and the visual analogue scale score and scoliosis angle at 6 months after surgery were significantly improved compared with those before operation in both groups (P < 0.001). There was no significant difference in visual analogue scale score and scoliosis angle between the two groups at 6 months after operation (P > 0.05). (3) From the perspective of biomechanics and clinical efficacy, unilateral bone-filling mesh container approach is more effective than bilateral bone-filling mesh container approach in treating osteoporotic vertebral compression fracture. [ABSTRACT FROM AUTHOR]

The material constants of wood required for finite element analysis (FEA) are usually calculated using small clear specimens. However, defects, such as knots and slope of grain affect the strength reduction in the fullsize specimens. Consequently, an error occurs if only the material constant calculated from the small clear specimens is used to predict modulus of rupture (MOR). Therefore, in this study, the MOR reduction coefficient according to defect was obtained through the bending test of the full-size specimens and applied to the FEA, in addition to the material constant from the small clear specimens. The maximum bending moment section was measured for a 3-section four-point load, and defects in the outermost tension layer were measured for laminated timber and glulam. The result of the bending test confirmed that MOR also decreased as the size of the defect increased. Therefore, when predicting MOR, a strength reduction ratio according to visual grade was applied. The MOR predicted FEA was twice as large as the actual MOR before defect correction, but the prediction error after defect correction was greatly reduced to 8%, thus increasing the prediction accuracy. [ABSTRACT FROM AUTHOR]

Modern solid wood armchairs are developing in the direction of simplicity and lightness, and favored by the market. However, the low mechanical strength of the connecting joint of cantilevered handrails is an issue that needs to be improved. In this study, the armrest joints of a cantilever armchair made by beech (Fagus orientalis Lipsky) were examined. To improve the mechanical strength of handrail joints, three novel joints were proposed including dovetail tenon, cross-stepped tenon, and rear plug corner tenon. The finite element analysis (FEA) was used to compare and analyze the five joints to obtain the optimal joint. Finally, experimental tests were conducted to verify the results of the FEA. The novel cross-stepped tenon had better mechanical performance, i.e., bending moment capacity and stiffness, than other joints evaluated. The maximum load of the novel cross-stepped tenon was greater than that of the commonly used tenon. In conclusion, the cross-stepped tenon was most suitable for cantilevered handrail joint of chair. This study will contribute to the structural design of modern solid wooden chairs. [ABSTRACT FROM AUTHOR]

The response of laterally loaded piles installed near the crest of clay slopes is analysed. Three-dimensional finite element analyses are presented for piles at various distances from a slope crest and for different pile shape. The results of these analyses are used to study the variation of the pile displacement, the bending moment of the pile and the soil resistance in relation to pile to slope distance and pile shape. The obtained results show that the proximity of slope significantly affects the lateral load capacity of the piles but not significantly when the piles are placed at 7D (where D is pile diameter) or greater from the slope crest. Furthermore, the lateral soil resistance on the ground surface for circular piles is larger than that for rectangular piles at the same lateral load in level ground. The decrease rate of lateral soil resistance on the ground surface for circular piles gets faster as the slope ratio and load level increase. [ABSTRACT FROM AUTHOR]

In this paper, an energy-conserving finite element method is developed and intensively analyzed for a class of nonlinear fourth-order wave equations in a general sense for the first time, where the two-level, Crank-Nicolson type of temporal discretization scheme is designed to cooperate with the Lagrange finite element approximation in space in order to achieve the conservation of discrete energy at each time step. The energy conservation is crucial in engineering field to preserve the total energy as constant for dynamic vibration problems of beams and thin plates that can be modeled by the presented wave equations. In addition, the optimal spatial convergence properties in both L 2 - and H 1 -norm and the second-order temporal approximation rate are obtained for finite element solutions of u (deflection), Δ u (bending moment) and/or u t (deflection speed) at the same time. Numerical experiments are carried out to validate all attained theoretical results. [ABSTRACT FROM AUTHOR]

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article examines the mechanical behavior of steel endplate beam-to-column joints with different stiffeners under bending moment. This type of connection is commonly used in steel frameworks to transmit loads from beams to columns. In frame design procedures, engineers tend to consider beam-to-column joints either ideally pinned or fully rigid. The present study aims to show their semi-rigid behavior by analyzing the characteristics of the relation between the bending moment and the rotation of the studied connection. The analysis is based on the development of a finite element model considering the material, geometrical and contact nonlinearities between the components. Three types of stiffeners are introduced in different positions to investigate their effect on the global behavior of the joints. The moment rotation curve is defined together with the procedure of determination of the initial rotational stiffness, the elastic and plastic moments of the connection. The numerical model is validated by comparing the moment rotation curves with those of similar studies available in the literature and also with the design approach proposed by Eurocode 3. The obtained results have showed that the use of stiffeners in the column web or on the endplate increases significantly the rigidity of the studied connection. The failure modes have been discussed in detail for each configuration with respect to the rotation capacity and the initial stiffness. Finally, the model has been used to show the influence of three bolts classes on the ultimate load of the joints and the deformation of the endplate and bolts at failure. [ABSTRACT FROM AUTHOR]

To prevent marine risers' resonance and eliminate potential threats, sufficient inherent dynamic characteristics such as natural frequency, modal displacement, slope, bending moment, and shear are necessary to be calculated and analyzed. However, most studies calculate the natural frequencies and modal displacements directly rather than the modal slopes and forces. The additional calculations of modal slopes and forces likely result in issue complications, time-consuming, or even errors especially when the boundaries at both ends are solved by a finite difference method. To solve the above problems, a state-vector approach is developed herein based on the precise integration method. Two traditional methods, i.e., differential transformation method and finite element method, are utilized to verify the validation of the approach. The modal state vectors of a marine drilling riser, i.e., not only modal displacements but also modal slopes, bending moments, and shears, are studied in detail under four classic cases according to the hard and soft hang-off modes and the deployment and retrieval processes. Besides, the natural frequencies versus the riser suspension lengths are investigated during the deployment and retrieval. The critical resonance suspension lengths of the riser are discussed via a double-peaked sea irregular wave spectrum. Based on the analyses presented in this study and their generic findings, powerful tools can be designed to prevent riser resonance and associated threats in operation. [ABSTRACT FROM AUTHOR]

The residual strength of denting- and fracture-damaged box girders were experimentally and numerically investigated. The experiments were conducted under a pure bending moment using the four-point bending test method. The load, deflection, and strain were measured. The strains of the extension structures were also measured, and the frictional forces between the model and the supported round bar were estimated. Test models consisting of two groups were fabricated. These groups were designed to estimate the residual strength of denting- and fracture-damaged models. The damage was induced by releasing a striker using a drop-testing machine to consider the dynamic effect. Additionally, numerical analyses were performed via a nonlinear finite element analysis, where the measured initial imperfection data and welding residual stresses were considered. The ultimate longitudinal moments that considered the frictional force of the round bars were reduced by 12% (on average) compared with those obtained by neglecting the frictional forces. [ABSTRACT FROM AUTHOR]

We seek for novel electronic phenomena by using external strain engineering, namely, by the application of external uniaxial strain. A piezoelectric-based uniaxial strain cell has been recently developed by Hicks et al. and successfully utilized for studies of various unconventional superconductors. Here, we propose a modified design that minimizes effects originating from the asymmetry of the strain cell design, in particular with minimal bending moments, by placing the sample at the axis of mirror symmetry of the device to balance out the reactive forces. Results of finite element analyses indicate that placing the sample offset to the axis of the mirror symmetry indeed causes an increase of strain inhomogeneity up to 10%, both at room temperature and at 4.2 K. Furthermore, we found that this bending reduces the overall achievable strain down to 30% of its maximal value without the bending. We also experimentally demonstrate the potential of our constructed device by tracking the displacement of the anvils of the strain cell with a parallel plate capacitor. The full range of motion of the piezo-stacks were demonstrated at room temperature. With a sample and at 0.9 K, we achieved a uniaxial strain of − 1.5 %, which is enough to induce electronic change in typical materials. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan University of Science & Technology, Natural Science is the property of Editorial Office of Journal of Henan University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hot stretch bending (HSB) was an advanced manufacturing process for fuselage structure of aircraft. In this work, U shaped titanium extrusion hot stretch bending was investigated by applying numerical and experimental approaches. Hot uniaxial tension was tested to investigate the deformation behavior. Sequential coupling finite element model setup between electro-thermal coupling and thermalmechanical coupling was established to optimize U shaped extrusion stretch bending process parameters for electro-thermal-mechanical coupling. The optimal process parameters for hot stretch bending of U shaped extrusion were determined and the springback after hot stretch bended was evaluated. In the bending experimental verification, under the condition of the strain neutral layer Rn of mold was equal to 829.5μm, the angular springback rate was 0.56%, which is in a reasonable agreement with simulated result of 0.44%. [ABSTRACT FROM AUTHOR]

The practice of deep-braced excavation in congested urban environments involves frequently buried pipelines, which can exert a significant effect on the performance of the excavation. The objective of this paper is to investigate the performance of a 12.5-m-deep-braced excavation spanned by two shallowly buried large-diameter pressurized pipelines. A suspension structure is installed within the excavation to protect the in situ pipelines during the construction. The excavation performance is investigated by performing a three-dimensional finite element analysis. The finite element method is verified based on the observations at the site. The results indicate that, as expected, the excavation support structures displace together with varying degrees of deformation toward the excavated area. The strut shear forces are found to be distributed axially in linear manners, while the strut bending moments are in symmetric manners. The benefit of using the proposed pipeline suspension structure is demonstrated. By using this structure, pipeline deformation can be well controlled, and the structural integrity and safety of the pipelines can be ensured. This benefit depends on the convenient operation in that the elevation of the cork base of the pipeline suspension structure is stably lowered during the construction process. [ABSTRACT FROM AUTHOR]

Diagnostic load testing refers to the use of the measured historical responses of the structure in the field data to better understand its dynamic and static structural behaviours. It is important and necessary to predict the health state, load capacity, and aging of the structure by updating the finite element (FE) model, which can give useful information to aid the design of retrofits and the maintenance of the existing bridge in the future. The paper presents an update of the full-scale FE model for the reinforced concrete (RC) bridge structure over the seawater river based on the experimental strains under the static load testing in which the representative FE model of the actual structure is determined from the optimisation procedures. The optimisation variables are applied, including the cross-sectional properties and concrete material calibrated through the genetic algorithm (GA) optimisation in the MATLAB software, which interfaces with the FE modelling in the scripting of the SOFISTIK TEDDY software automatically. The bending moments at the mid-span of the RC girders are determined in the FE modelling to compute stresses, which are compared with the measured stresses through optimisation scenarios with a percentage error of the objective function less than 10%. The measured data of concrete strains are recorded from reusable strain transducers installed on the mid-span girders for every bridge span, which are used to calibrate the bridge model in static load testing. The novelty of the solution is to implement innovative techniques using field data as an improved approach for calibrating automatically the analytical FE model parameters of all RC spans of the bridge until its static behaviours are very similar to those of the actual bridge. The final updated FE modelling is used to apply truck load configurations according to bridge design standards such as the AASHTO specifications, which can predict the load limits of the existing bridge structure more accurately and reliably. These proposed approaches can be applied to large bridges as well as complex structures with supporting FE analysis software and data processing software. [ABSTRACT FROM AUTHOR]

The present study assessed the Bailey Bridge's condition and investigated its adaptation as a permanent structure, targeted the Acrow Bailey Bridge in Japan. Field diagnostic loading experiments were performed under various loading conditions, such as dynamic and static loading tests. The onsite data were obtained using a transducer, friction strain gauge, target measurements for the image processing approach, and accelerometer. From the field measurements, the deflection and stresses of the bridge were found to operate within the linear elastic region. The bridge was then accurately modeled based on the in situ geometric configuration of the bridge, and Finite Element Analysis was performed. The model's accuracy was validated with the onsite data under the linear elastic domain. The model was deployed to check for resistance of critical members. A nonlinear analysis based on the linear and nonlinear buckling method was performed to determine the subject bridge's Serviceability Limit State and Ultimate Limit State. The results showed that the first out-of-plane eigenvalue buckling analysis could monolithically assess bridge members. Further, the study established digital twin models resolve for historical data through in situ modeling measurements. Therefore, the findings obtained in this study highlight the bridge's Structural Health Condition, bearing capacity, and propose a framework for adaptation as a permanent structure. [ABSTRACT FROM AUTHOR]

The safety of the piping systems used in any nuclear or thermal power plant is essential to the environment and also to the people involved. Pipe bends are one of the critical components of the piping system. Hence, fatigue life estimation becomes primary focus when the designing pipe bends for their safety limits. The current study uses finite element analysis and the revised manson universal slope method to estimate the life of elbows under in-plane opening and closing cyclic bending moment. The estimated fatigue life was compared with low-cycle fatigue tests in the literature. The displacement of 20 mm was given as input to estimate the number of cycles. The principal stresses were obtained on the highly strained node of the finite element model to locate the crack and its direction accurately. The elbows with thinning have a reduction in the fatigue life of about 19%. [ABSTRACT FROM AUTHOR]

PE pipeline is widely used in urban gas pipe network. The carrying capacity of PE pipe with local thinning defects is an important means to ensure its safe operation.Firstly, the initial elastic modulus and yield stress are fitted by the finite element method to obtain the carrying capacity of internal pressure, bending moment and axial force, the BP neural network model including relative depth C/T, relative axial length 2A/√RT, relative circumferential angle 2θ/π and dimensionless parameters c, and combined with GA optimized BP neural network model. It can be found: the predicted value of the model is relatively consistent with the simulation results, which shows that the method of GA optimization of the BP neural network model is feasible,which provides an effective method for the intelligent safety evaluation of the PE pipeline with local thinning defects. [ABSTRACT FROM AUTHOR]

Copyright of Railway Investigation & Surveying is the property of Railway Investigation & Surveying Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new type of precast pile, namely steel strand square piles with reinforcement (PRS), is proposed in present study, which uses steel strand as a prestressed reinforcement and is equipped with hot-rolled reinforcement. Two kinds of full-scale pile specimens with different reinforcement were constructed to study the bending performance by the full-scale tests. The finite element model was also performed to study the differences in bending resistance, deformation capacity, crack resistance, and failure mode because of the reinforcement ratio. The results show that the steel strand in the pile was not pulled off, and the concrete in the compression zone was crushed. The finite element analysis results are close to the results of the full-scale test of the piles, which can simulate the flexural performance of the pile well. The experimental results were closer to the theoretical calculation of the cracking moment. The ultimate bending moment value is about 25% more than the theoretical value. The parametric analysis shows that for the PRS with 0.27% prestressed reinforcement, the best bending performance is achieved with 0.64% non-prestressed reinforcement. For the PRS with 0.64% of non-prestressed reinforcement, the best bending performance is achieved with 0.37% of prestressed reinforcement. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China University of Technology (Natural Science Edition) is the property of South China University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper reports a hybrid modular floating structure (HMFS) system preliminarily designed for mild marine environment. It is composed of a certain number of inner semi-sub modules and outermost box-type modules. The box-type modules are connected to adjacent semi-sub modules with hinges and additional Power Take-Off (PTO) damping systems. The hydrodynamic characteristics of several representative simplified serially connected HMFS systems under typical sea conditions are compared. The functions of the outermost module, the effects of different outermost module types and the expansibility of the HMFS system are emphatically analysed. The results indicate that compared with the outermost semi-sub module, the outermost box-type module is more effective in reducing the motion responses of inner semi-sub modules, connector forces and mooring forces. The additional PTO damping systems can produce substantial wave energy. The HMFS system shows good expansibility for mild sea zones. Abbreviations: HMFS, Hybrid Modular Floating Structure; VLFS, Very Large Floating Structure; RMFC, Rigid Module and Flexible Connector; MOB, Mobile Offshore Base; FEM, Finite Element Method; PTO, Power Take-Off; MFS, Modular Floating Structure; Ks, Pitch Elastic Stiffness; Kp, Pitch Damping Coefficient; DOF, Degree of Freedom; Fx, Horizontal Force of Connector; Fz, Vertical Shear Force of Connector; My, Pitch Bending Moment of Connector [ABSTRACT FROM AUTHOR]

The finite element analysis model is developed to investigate the bending capacity of the concrete-filled micro-steel-tube (CFMST) piles. First, the classical elastic-plastic model is employed to describe the constitutive relation of the steel material, while the plastic damage model is applied to portray the concrete material. Then, the three dimensional (3D) finite element numerical model for analyzing the flexural bearing capacity of the CFMST pile is established by virtue of the ABAQUS software. The reliability and accuracy of the present numerical model is carefully validated by comparing with the experimental data. The influence of the concrete strength grade, wall thickness of the steel tube, external diameter of the steel tube, and yield strength of the steel are analyzed in detail. It is shown that increasing the wall thickness/external diameter of the steel tube and the yield strength of the steel can greatly improve the flexural bearing capacity of the CFMST pile. Finally, a concise formula for the ultimate bending moment of the CFMST pile is proposed, which could be directly applied into the future engineering design. [ABSTRACT FROM AUTHOR]

Detailed three-dimensional numerical models considering concrete indentation, bolts, elastic gasket (EG) and sealing gasket (SG) are established for the segmental joint with gaskets, and the load tests of the joints with EG and without EG are simulated and compared. The results reveal that the bearing performance of the joint with EG is very complex. In sagging moment scenarios, it can be divided into four stages by three key points "EG starts to open", "joint external edge starts to contact" and "EG fully opened". In hogging moment scenarios, it can be divided into three stages by two key points "SG opened" and "EG starts to open". The EG has a significant effect on the joint bearing performance. It can soften the joint, which leads to the result that the average bending stiffness and ultimate bearing capacity of the joint with EG are evidently smaller and weaker than those of the joint without EG. With decreasing the joint axial force, this softening effect tends to be more obvious. Besides, for the two joints, the ultimate states of the joints subject to the bending moments are both that the concrete at the joint edges yields firstly, and it is necessary to protect or strengthen the corresponding concrete. [ABSTRACT FROM AUTHOR]

Trapezoidal corrugated web girder (TCWG) is widely used in many fields. The elastic transverse bending moment which exists in the flange influences the mechanical properties of TCWG. For the simply supported TCWG, the equivalent load method is proposed in this paper. And the transverse bending moment calculation model is established. The calculation formula of the elastic maximum transverse bending moment under the most unfavorable geometrical situation is deduced. The formula is consistent with the existing literature. ANSYS finite element method is used to calculate the elastic transverse bending moment of the flange. The calculation results of formula are in good agreement with the finite element analysis. The existence of transverse bending moment is verified by the experimental data. The physical significance of the transverse bending moment as the integral bearing performance index of the TCWG is revealed in this paper. This paper provides a reference for further analysis of transverse bending moment of simply supported TCWG. [ABSTRACT FROM AUTHOR]

The cofferdam method is generally applied in the construction of underwater pier foundation in bridge engineering, and the pouring of bottom sealing concrete is one of the important links in the construction of the cofferdam. The bottom sealing concrete can prevent water seepage and balance the main body of the cofferdam, and its structural size and construction quality have a great influence on the above functions. Under the condition of large water level difference, it is difficult to determine the reasonable thickness of the bottom sealing concrete. There are few related studies in this field, and there is a lack of systematic summary of calculation theory. This work theoretically deduces the approximate solution of ultimate bending moment and ultimate stress of the bottom sealing concrete, introduces two different calculation methods, systematically summarizes the calculation methods of three kinds of ultimate stress, analyzes the calculation methods of ultimate bonding force, and uses ANSYS finite element software to simulate a specific bottom sealing concrete model, and compares it with the theoretical calculation results. The maximum stress obtained by the approximate solution is closer to the actual monitoring data than the traditional method, and the calculation method of the bonding force can be used to make a rough estimate. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Retaining pile structure is commonly utilized in excavation maintenance design. In recent years, the long-short combined retaining piles have received more and more attention. According to the actual deep excavation engineering, the working mechanism of the long-short, long-double-short, and long-triple-short combined retaining piles was tested in the field. Based on the field test parameters, the finite element model of the test area was established and the simulation results were verified, and the effects of short pile length and pile spacing on bending moment, horizontal displacement of piles, surface settlement, and excavation bottom heave were further investigated. The results show that the bending moment of the long pile is larger than the short pile. The bending moment of the long pile and short pile increases gradually with the increase in the number of short piles. When the combination changes from combination 1 to 3, the peak moment of the long pile and short pile increases by 15.8% and 15.2%, respectively. The maximum displacement is near the pile top, combination 3 has the largest horizontal displacement, and the peak displacement of the long pile and the short pile is 17.21 mm and 17.87 mm, respectively, but almost no effect exists on the horizontal displacement below the excavation bottom. In addition, reducing short pile length and increasing pile spacing will increase bending moment and horizontal displacement of the long and short piles to a certain extent, and this phenomenon is mainly concentrated above the excavation bottom, the influence of short pile length and pile spacing on surface settlement and excavation bottom heave can be ignored. [ABSTRACT FROM AUTHOR]

Shear reinforcement is one of the common measures used to strengthen slab–column connections. It can make the joint's load capacity increase. However, when the connection is subjected to an unbalanced bending moment, the reduction effect of the shear reinforcement on the bending moment is worth investigating. Nonlinear finite element analysis was performed on reinforced concrete slabs with shear reinforcement for various moment-to-shear (M/V) ratios. The effects of the number and diameter of shear reinforcement and different loading methods on the slab were investigated, as along with a correction to the ACI-318 and China Concrete Structure Design code GB50010 formula for the moment transfer coefficient. The 3D finite element modeling was performed using appropriate element types and a constitutive model for concrete. The concrete damage plasticity model parameters were calibrated using the experimental results of a specimen. The amount of shear reinforcement had a certain contribution to the strength of the slab, but the diameter of the shear reinforcement had little effect. The plate's bearing capacity decreased as the M/V increased. The corrected moment transfer coefficient formula demonstrates that M/V is positively correlated with the coefficient and that the calculated values specified in ACI-318 and GB50010 are overly conservative. [ABSTRACT FROM AUTHOR]

Piled raft foundations can be effectively used when their hardness and bearing capacity are estimated sufficiently, and the total settlement, or the differential settlement, of the rafts, stays within a certain limit value. This research applies a 3D finite element method to analyze the response of the flat raft foundation when a minimum number of piles is installed under the raft foundation. The results show that when the pile length changes alternately (between the long pile and short pile), the settlement, the differential settlement, positive and negative moments, and the maximum shear force of the raft increase. The distance between the piles plays an important role in the performance of the piled raft foundation when the pile length is changed. It has a strong influence on the maximum settlement, differential settlement, bending moment of the raft, and distributes the load applied on the pile. In addition, the configuration of the piles is an important factor in the design of piled raft foundations. One reasonable pile configuration includes short piles being placed on the outside, and pile length being increased gradually from the outside to the center of the raft. The raft can also significantly influence the settlement between the center and the rim of the raft. When the thickness of the raft is increased to a certain value, the level of settlement is not significant. On the other hand, the raft's thickness has a small influence on the settlement of the piled raft foundation, it can affect the bending moment of the raft. [ABSTRACT FROM AUTHOR]

The objective of this paper is to present the application of equivalent single layer (ESL) approach for the ultimate strength assessment of ship hull girder in the context of numerical finite element (FE) simulations. In the ESL approach, the stiffened panel is replaced with a single plate, which has the equivalent stiffness of the original panel. Removal of tertiary stiffening elements from the numerical model facilitates time-savings in pre-processing and FE analysis stage. The applicability of ESL approach is demonstrated with two case studies, one compartment model and full-sized double hull tanker model in intact and damaged conditions. The damage extents are determined based on the international association of classification societies from common structural rules (IACS-CSR) for oil tanker. Ship hull girder is exposed to distributed pressure with the sinusoidal shape that bends the hull girder. This pressure load is applied separately to bottom and side structures to obtain the vertical and horizontal bending moments of the hull girder, respectively. Ultimate strength predictions obtained from ESL approach are compared to full three-dimensional finite element method (3D FEM) and IACS incremental-iterative method. The comparison between different methods is provided in terms of longitudinal bending moment and cross sectional stress distribution. Overall, ESL approach yields good agreement compared to the 3D FEM results in predicting the ultimate strength of ship hull girder while providing up to 3 times computational efficiency and ease of modeling. [ABSTRACT FROM AUTHOR]

A finite element formulation of solving the stability problems for composite cylindrical shells is presented, taking into account the momentness and nonlinearity of their subcritical stress-strain state. The stability of a circular cylindrical shell made of a polymer composite material under combined loading by torsion and bending moments is investigated. The influence of the methods of laying monolayers, the nonlinearity of deformation on the critical loads of the shell stability loss and the weight efficiency of composite shells in comparison with metallic ones is clarified. [ABSTRACT FROM AUTHOR]

The concept of pier-supported submerged floating tunnel (PSFT) is feasible if the water depth is within 100 m. In this study, semi-analytical solutions are proposed for determining the seismic responses of a tunnel tube in a PSFT subjected to vertical excitation. The tunnel tube consisting of tube segments and flexible joints is simplified as beam components connected through bending springs. The supporting system comprising bearings and piers is regarded as a series of discrete Kelvin elements. Seismic action is considered as the inertia force and hydrodynamic pressure is calculated by the Morison equation. The tunnel tube displacement is derived by the modal superposition method. On this basis, the semi-analytical solutions of the displacement and bending moment of the tunnel tube are deduced using the Runge–Kutta method. The finite element method is employed to examine the validity of the proposed solutions. Furthermore, the effects of the fluid, flexible joints, and damping ratio are discussed. The results show that the Froude–Klylov force can significantly reduce the response amplitude, and the hydrodynamic mass force can alter the response frequency under real seismic input motion. Flexible joints can adjust the bending moment distribution in the tunnel tube. With the adoption of flexible joints, the hogging moments at the bearings considerably decrease. The change in damping ratio also have substantial effects on the structural seismic response. [ABSTRACT FROM AUTHOR]

This study investigates the load-carrying mechanism and proposes precise strength prediction methods for hole threads in Thread-fixed One-side Bolts bolted curved T-stubs to circular steel tube connections. A series of parametric analysis was performed with an advanced 3D finite element model considering critical parameters including tube wall thickness, bolt angle and bolt size. The axial load distribution along the hole threads and the shear stress distribution at the thread root were analyzed in detail. It was found that there were three typical load distribution patterns along hole threads, which were (1) linear pattern; (2) concave parabola pattern; and (3) convex parabola pattern, and the ratio of bolt stiffness to tube wall stiffness was identified as the pivotal factor affecting the axial load distribution. Meanwhile, the analysis results indicated that the bending moment on the TOBs did not affect the load distribution along hole threads, but led to a non-uniform stress distribution along the thread in the same turn. In the end, the prediction formulas for the carrying capacity of hole threads are presented by modifying Yamamoto's equation based on the analysis findings. The formulas are validated against the finite element analysis results and previous test results. The prediction can reach the highest accuracy when adopting the proposed failure criterion 2, with average errors of − 0.001 and − 0.002, respectively, demonstrating the accuracy and reliability. • An advanced 3D finite element model for bolted connections was developed. • The load distribution along hole threads were analyzed in detail. • Three typical load distribution patterns along hole threads were found. • Proposing methods to predict the load-carrying capacity of hole threads. [ABSTRACT FROM AUTHOR]

The seismic behaviour of hybrid coupled walls (HCWs) made of a single reinforced concrete (RC) wall connected to two steel side columns through steel links, named as single-pier HCWs (SP-HCWs), is studied through nonlinear finite element simulations. The design concept is that the steel links are intended to work as dissipative elements while the steel side columns and the RC wall should remain elastic. Given that previous studies highlighted difficulties in avoiding damage at the base of the RC wall due to the concentration of bending moment, this study focuses on a special configuration providing very limited damage at the base of the RC wall that could be rapidly and economically repaired. The original scheme of SP-HCW with fixed base is modified introducing a hinged connection combined with vertical steel elements, called corner components. A ductile design methodology is proposed and applied for proportioning 54 case studies with different building heights, coupling ratios, height-to-length ratios of the RC wall, in addition to different base conditions (fixed base, hinged base with corner components designed as non-dissipative elements, hinged base with corner components designed as dissipative elements). Results of nonlinear finite element analyses validate the design methodology and highlight the potentialities of the proposed solutions, showing the benefits of a hinged base with corner components. • The seismic performance of single-pier steel and concrete hybrid coupled walls is studied. • Focus is made on alternative hinged base solutions to protect the wall from damage. • A seismic ductile design procedure is proposed and applied to a wide set of case studies. • Results provide insights into the benefits of the developed base configurations. [ABSTRACT FROM AUTHOR]

Six T-shaped welded multi-partition composite members were tested under eccentric compression loading by considering the influence of eccentricity and eccentric angle. The test results showed that no weld tearing occurred when the specimen was damaged, indicating that the two vertical welds could ensure the overall working performance of the specimen. The specimens exhibited the smallest bearing capacity when failing along the asymmetric axis, which was the most dangerous situation. The parametric analysis is conducted by a verified finite element model considering the influence of the slenderness ratio, section height-to-width ratio, section depth-to-width ratio, concrete and steel grade, steel ratio, and eccentric angle. If concrete contributes a larger proportion to the bearing capacity, the interaction curve of axial force and bending moment tends to protrude. Conversely, the interaction curve of axial force and bending moment gradually shrinks as the slenderness ratio increases. Based on this observation, a calculation method of T-shaped welded multi-partition composite members under eccentric compressive loading along the asymmetric axis is proposed by considering the effect of the slenderness ratio. Formulas for bearing capacity under biaxial eccentric compression are proposed based on the results of the parametric analysis. • Eccentric compression of T-shaped welded multi-partition composite members was studied through experiments and FE analysis. • The measured torsion angle confirms the good torsional capacity of T-shaped composite members. • The effects of the slenderness ratio and biaxial eccentricity on the bearing capacity of the specimen are studied. • The N - M curve of T-shaped composite members under eccentric compression loading along the asymmetric axis is proposed. [ABSTRACT FROM AUTHOR]